The present invention relates to, and is an improvement of, the mobile pumping apparatus described and claimed in my prior U.S. Pat. No. 4,751,969, hereinafter referred to as the '969 patent. The invention relates generally to an apparatus for removing fluids from a well. More particularly, the present invention relates to a mobile apparatus capable of lifting fluids, particularly oil, out of a well using a swab mounted on the free end of a cable which is run down the well and then retrieved, bringing the fluid up with it, and collecting and storing the fluid as it is removed from the well. Such an apparatus is also of considerable utility for use in cleaning and other maintenance operations in oil wells. The improvements described herein facilitate the manufacture of the apparatus, increase reliability, decrease the likelihood of damage to the well or the sticking of the swab in the well, and promote efficient removal of fluid from a well.
Although the apparatus described in the '969 patent has given (and continues to give) years of dependable service, that very experience has demonstrated certain areas in which certain disadvantages and/or limitations have been identified. For instance, the apparatus described in the '969 patent requires that the entire front end of the apparatus, e.g., the standpipe and boom assembly, be moved by a combination of hydraulics and movement of the vehicle to which the apparatus is mounted to align the standpipe into which the fluid flows as it is removed from the well with the wellhead. It is a novel feature of the boom assembly of the present invention that the standpipe is mounted to a telescoping boom which includes a hydraulic cylinder for extending the standpipe into position over the well, after picking up the well cover using the boom assembly of the present invention without re-positioning the vehicle to which the boom assembly is mounted. These novel features facilitate speedy removal of fluid from a well. The economics of removing oil from stripper wells (wells which produce less than about 10 barrels a day) requires that extraction be accomplished quickly.
Not only does the present invention incorporate an improvement in the boom, but also improvements to the standpipe assembly help to make the present invention less expensive to build and operate. The standpipe assembly of the present invention includes a standpipe which can be raised into and out of engagement with a wellhead, thereby eliminating the necessity for heavy hydraulics capable of pivoting the entire standpipe assembly into and out of engagement with the wellhead as is the case with the apparatus described in my prior '969 patent. Not only does this construction speed the alignment of the standpipe over the wellhead by eliminating the arc through which the standpipe assembly pivots in the case of the apparatus described in my prior patent, but also the elimination of the heavy hydraulics results in overall weight savings and the elimination of unnecessary complication, reducing fabrication costs and increasing economy of operation.
The present invention also contemplates improvements to the swab bar of the '969 patent to decrease the likelihood that the swab bar will lodge down in the well. The swab bar described in the '969 patent occasionally lodges in a well with the swab cups mired in the sand. The boom assembly of the present invention includes a swab bar with a lead base as the leading part of the swab bar. The heavy lead base is therefore the first portion of the swab bar to encounter any sand which may be present and either break the sand loose or stop the swab bar before the swab cups become lodged in the sand.
Even with these improvements to the swab bar, experience has demonstrated that the swab bar still occasionally lodges in the well. The boom assembly of the present invention therefore includes a further improvement for remedying that eventuality in the form of the mounting of the winch on a carriage movable by a hydraulic cylinder between first and second positions. In this manner, additional upward force can be exerted on the swab bar beyond that which the winch is capable of exerting by sliding the winch carriage from first to second positions to assist in either dislodging the swab bar or literally pulling the swab cups off of the swab bar, thereby freeing the swab bar.
These improvements to the swab bar also make possible certain improvements to the slack detection means described in my prior patent. Specifically, because the improved swab bar is more likely to penetrate, for instance, accumulated sand in the well and is, in general, less susceptible to downhole conditions, it is possible to detect smaller changes in the tension in the cable from which the swab bar is suspended. To take advantage of that capability, the pulley which rides on the cable and which comprises a primary portion of the slack detection means has been repositioned on the cable from the horizontal portion of the cable to the vertical portion of the cable, thereby increasing the sensitivity of the slack detection means.
It is, therefore, a primary object of the present invention to improve upon the invention described in the '969 patent.
Another object of the present invention is to provide an apparatus that is more easily and inexpensively manufactured and operated than the apparatus described in that prior patent.
Another object of the present invention is to provide a means for the operator to quickly remove a well cover remove the oil from the well, open and close a wellhead valve, and/or place the well cover back on the well, all without the need for moving the vehicle or for the operator to leave the vehicle.
Another object of the present invention is to provide an apparatus that will reduce the probability of the sticking of the swab bar in the well, for instance, when the swab bar encounters sand which may be present in the well.
Another object of the present invention is to provide the means for applying more pulling power to the cable than is produced by the winch onto which the cable is wound to assist in removing the swab bar when stuck in the well.
Other objects of the present invention will be apparent to those skilled in the art from the following detailed description of the invention.